This invention relates generally to the field of seals configured to seal large annular gaps, and more particularly to elastomeric annular seals configured to be mounted on a missile for sealing the annular gap between the surface of a missile and its launch tube or canister.
Launch seals configured to fill the annular gap between the outer surface of a missile and the inner surface of its launch tube or canister are of basically two types: those configured for mounting to the inner surface of the canister and those configured to be mounted to the outer surface of the missile or to a deployable ring attached to the missile. Canister mounted seals are characteristically stretched in situ within the annular gap between missile and canister and remain within the canister upon launch of the missile. The missile mounted seal, on the other hand, is characteristically compressed in situ and is launched with the missile. Both the canister mounted seal and the missile mounted seal must, however, perform the functions within the canister of providing a sufficient sliding gas seal within the annular gap against excessive launch pressure leakage, and of resiliently holding the missile within the canister. Representative of prior art seals of the canister mounted type are such as those disclosed by or referenced in U.S. Pat. No. 4,033,593 to Molnar et al. Typically, solid elastomers are selected for the annular seals because of the flexibility and high strength which characterize these materials.
In the relaxed condition, the outside diameter of a missile mounted launch seal must be larger than the inside diameter of the canister in order to provide the desired seal. Therfore, such a seal must be compressed prior to loading of the missile into the canister and remain somewhat compressed in place. To a first approximation, the solid elastomers suitable for use as launch seals are incompressible. Therefore, a missile mounted seal having a substantially constant annular cross section will buckle unpredictably when circumferentially compressed. A significant pressure leak would then occur at the buckled locations around the seal periphery. To avoid this eventuality, the novel missile mounted seal of the present invention provides, in its various embodiments, means for controlling the buckling of the seal upon compression thereof, without allowing excessive pressure leakage around the periphery of the seal in the buckled condition.
It is therefore, an object of the present invention to provide an improved seal configured to seal large annular gaps.
It is a further object of the present invention to provide an improved seal for sealing the space between a missile and its launch canister.
It is yet a further object of the present invention to provide a missile mounted launch seal configured for accommodating compressive hoop strain imposed thereon by providing controlled buckling thereof in situ, without allowing excessive launch pressure leakage.
These and other objects of the present invention will become apparent as the detailed description of specific embodiments thereof proceeds.